Near Field Communication (NFC) is a standard allowing wireless communication in a Radio Frequency (RF) band between portable devices, such as smartphones, or between a portable device and a fixed device (an NFC terminal). For the communication, for example, a portable device having an NFC circuit is placed in the vicinity of the NFC terminal (e.g., as close as a distance of about 10 cm or less) or is brought into contact with the NFC terminal. Then, an RF wireless communication channel is established between the portable device and the NFC terminal, so that the portable device may perform NFC communication with the NFC terminal.
According to the standard of near field communication, the NFC communication uses a frequency band of 13.56 MHz, and RF communication is accomplished within a distance of about 10 cm or less. From this viewpoint, the NFC communication is distinguished from other wireless communication in different RF bands. For example, Bluetooth communication is used to communicate within a distance of about 1 m using a frequency band of 2.4 to 2.5 GHz. Wi-Fi communication is used to communicate within a distance of about 20 m or less using a frequency band of 2.4 or 5 GHz. LTE communication frequently used for data communication of a smartphone uses a frequency band of about 700 MHz to about 2.5 GHz although the frequency band varies by region or country. Compared with other RF wireless communications, the NFC communication uses a considerably low frequency band. Further, the NFC communication provides wireless communications between devices within a very short distance.
Recently, a circuit and an antenna for enabling near field RF communication begin to be mounted in a smartphone. However, wireless communication circuits and components for providing various kinds of wireless communications (e.g., LTE communication, Wi-Fi communication and Bluetooth communication) are housed in the smartphone, and various kinds of antennas are also mounted in the smartphone. In addition, components that may affect the wireless communication, such as a battery and the like, are also mounted in the smartphone. Accordingly, spaces for installing the NFC circuit or antenna are limited. There are also a lot of things to be considered in practice in designs of the antenna and the smartphone in order to satisfy various requirements required by standards of near field communications even under the limited condition of spaces.
The aforementioned description is intended to illustrate a general background of the present invention and does not constitute an admission that the described contents are prior arts.